Dotnet core 3.x based CMS

Piranha CMS for .NET Core

Small, lightweight, faster, open source and can run on Docker  with SQLite, SQLServer and SQLAzure  databases support .
Website
Github

Orchard Core

Open-source, modular, multi-tenant application framework and CMS for ASP.NET Core and can run on Docker  with SQLite, SQLServer and SQLAzure  databases support .

Website

Github

Oqtane CMS - Modular Application Framework for Blazor

Blazor based CMS

Github

Website